Dendritic crystals.
Crystals of this shape generally come from precipitation out of a solution. These are coated with a layer of oxide (all rare earths are reactive to some degree or another with air). It's now stored under mineral oil to prevent further oxidation. "George" reports: "Samarium oxide is particularly annoying because it crumbles off the sample and is like fingerprinting dust, it's so fine."Source:George (not 007) LazenbyContributor:George (not 007) LazenbyAcquired:20 November, 2002Price: DonatedSize: 0.75"Purity: 99.99%

Magnet.
Several different rare earths are used, typically in combination with iron, cobalt, or boron, to make very strong magnets. Neodymium-iron-boron magnets are stronger than this samarium-cobalt magnet, but it's still a pretty nice magnet for its size.Source:Ed Pegg JrContributor:Ed Pegg JrAcquired:20 November, 2002Price: DonatedSize: 0.4"Purity: <30%

Lump.
This sample arrived with a full set of lanthanides at a time when I was missing europium, terbium, holmium, ytterbium, and of course lutetium.

This very kind donation from Max Whitby of The Red Green & Blue Company in England completed my element collection, to the extent that it gave me a plausible sample of every element one can plausibly have a sample of. (The Red Green & Blue Company is selling a periodic table collection containing similar samples of the same stuff, and if you want a ready-made collection of elements, that's the first place I would look.)

Sample from the Everest Set.
Up until the early 1990's a company in Russia sold a periodic table collection with element samples. At some point their American distributor sold off the remaining stock to a man who is now selling them on eBay. The samples (except gases) weigh about 0.25 grams each, and the whole set comes in a very nice wooden box with a printed periodic table in the lid.

Hollow cathode lamp.
Lamps like this are available for a very wide range of elements: Click the Sample Group link below to get a list of all the elements I have lamps like this for. They are used as light sources for atomic absorption spectrometers, which detect the presence of elements by seeing whether a sample absorbs the very specific wavelengths of light associated with the electronic transitions of the given element. The lamp uses an electric arc to stimulate the element it contains to emit its characteristic wavelengths of light: The same electronic transitions are responsible for emission and absorption, so the wavelengths are the same.
In theory, each different lamp should produce a different color of light characteristic of its element. Unfortunately, the lamps all use neon as a carrier gas: You generally have to have such a carrier gas present to maintain the electric arc. Neon emits a number of very strong orange-red lines that overwhelm the color of the specific element. In a spectrometer this is no problem because you just use a prism or diffraction grating to separate the light into a spectrum, then block out the neon lines. But it does mean that they all look pretty much the same color to the naked eye.
I've listed the price of all the lamps as $20, but that's really just a rough average: I paid varying amounts at various eBay auctions for these lamps, which list for a lot more from an instrument supplier.
(Truth in photography: These lamps all look alike. I have just duplicated a photo of one of them to use for all of them, because they really do look exactly the same regardless of what element is inside. The ones listed are all ones I actually have in the collection.)Source:eBay seller heruurContributor:Theodore GrayAcquired:24 December, 2003Price: $20Size: 8"Purity: 99.9%Sample Group:Atomic Emission Lamps

More lumps.
This is a larger sample of samarium dendritic crystals. Why I have them is not entirely clear to me, but they were on my desk so I photographed them.

I chose this sample to represent its element in my Photographic Periodic Table Poster. The sample photograph includes text exactly as it appears in the poster, which you are encouraged to buy a copy of.

Element coin.
Dave Hamric sells element samples under the name Metallium. He's developed a line of coins struck out of various common and uncommon metals: They are quite lovely, and very reasonably priced, considering the difficulty of creating some of them.
Here is the back side of this coin (click either picture to see it larger):
Click the Sample Group link below to see many other coins made of various elements, or click the link to his website above if you want to buy one like this.Source:Dave HamricContributor:Theodore GrayAcquired:30 September, 2007Text Updated:30 September, 2007Price: $38Size: 0.75"Purity: >99%Sample Group:Coins

Guitar pickup.
For some reason guitar pickups are advertised as using samarium cobalt magnets instead of the more common neodymium iron boron variety, because they are "lower noise". I have no idea if this is true, but it sounds fishy to me.Source:eBay seller musicpartsguruContributor:Theodore GrayAcquired:17 April, 2009Text Updated:17 April, 2009Price: $60Size: 3"Purity: <30%

Insane mineral capsules.
These minerals capsules are called "Immune Boost 77", from Morningstar Minerals. They are either being incredibly honest, or they really don't understand what they're saying when they list what amounts to nearly the entire periodic table on the label, as the "trace minerals" they contain.

Some of them are just silly, like thulium, which has absolutely no biological function. Others are a bit scarier, like thallium and thorium that are deadly poisons, and tellurium, which makes you smell of rotten onions for weeks.

Basically what they've done is list everything that occurs in even trace amounts in mixed monazite sand, which is kind of what the stuff inside looks like. The only reason they aren't seriously harmful (I assume) is that most of these are not actually present in any meaningful quantity.

My attention is drawn to these and other similar mineral supplements every time I decide to see if anything interesting has popped up on eBay for one or another of the obscure rare earths. Generally speaking if you search eBay for those guys you get very little of interest unless you turn on the option to search the text of the item description as well as the titles. Then you get lots of trace mineral supplements that one can only hope don't actually contain them.

Himalayan sea salt.
There is a list of 84 elements that seems to pop up repeatedly in the ingredient lists of "natural" mineral products, supplements, pills, and the like. Even, it turns out, in salt. Here then is the list of minerals claimed to be found in all-natural organic Himalayan sea salt:

I wish someone would tell these people that, for example, neptunium and plutonium do not occur in nature at all, let alone in salt. Unless, I suppose, if you count nuclear fallout as a "natural" source of ingredients.
What bothers me most is what this says about the level of scientific literacy, both of the people selling the stuff, and the people buying it. Does no one actually read the list? Or do they read it an not realize how preposterous it is? It's enough to make you despair for the future of mankind.
Pretty salt, though.Source:eBay seller saltwondersContributor:Theodore GrayAcquired:28 March, 2009Text Updated:4 April, 2009Price: $15Size: 0.25"Composition:NaClSbCsDyErEuGdHfHoInLaLuNdPrSmScThTlTeTbTmYbY